Conventionally, as a rotary shaft seal for use in, e.g., compressors, a rotary shaft seal has been known in which first and second seal elements having an equal thickness are arranged so as to be curved in opposite directions along the shaft center to have a generally T-shaped cross section (see, e.g., PATENT DOCUMENT 1).
However, in recent years, with improvement in efficiency and upsizing of manufacturing apparatuses, pumps with high discharge capability have been required, and a rotary shaft seal used for such a pump also has needed to be used in a severe use environment requiring, e.g., high rotation speeds and low leakage. A conventional rotary shaft seal has a problem in which the radial load of the rotary shaft seal (force for compressing a shaft) is so high that the friction (sliding torque) is increased, and further has a problem in which a large amount of grease contained in a space between the first and second seal elements is lost, and thus, the depth of wear on each of the first and second seal elements is deep.